For quality control in the manufacture of semiconductor chips, particularly the manufacture of wafers with a diameter of 300 mm, integrated measurement techniques are increasingly used. In integrated measurement techniques, unlike in conventional stand-alone methods, the measuring device is directly connected to, and integrated in, the production equipment. This is to ensure that quality control is as close as possible to the process.
The integration of measurement techniques in the processing equipment is often highly complex, as it frequently requires modifications in both systems, i.e. in the processing equipment and in the measurement system, which in turn is connected with additional costs.
In 300 mm wafer technology, however, a high degree of standardization is found. The processing equipment is provided with so-called Equipment Front End Modules (EFEMs). The EFEM represents the interface between the chip factory and the processing tool and takes care of logistics, i.e. the automatic supply of the equipment with wafers. The EFEMs typically have at least two load ports, the dimensions of which are standardized. The wafer containers (Front Opening Unified Pods or FOUPs), which hold the wafers, are placed onto these load ports.
The EFEM further comprises a robot and at the back is coupled to the corresponding processing equipment. The EFEM comprises a wafer container (FOUP), transports the wafer by means of a further robot into the processing tool via a lock, and after processing delivers the wafer to another FOUP.
In principle, an EFEM can also have several load ports. The load ports can be readily interchanged. The EFEM is thus an ideal location for coupling a measurement device to processing equipment, since it enables the use of the existing logistics of the EFEM with robots to allow flexible integration of the measuring process in the production process.
Integrated measurement techniques make it possible to subject the wafer to input measurement prior to processing and final inspection after processing. This makes it possible to avoid further processing of bad wafers and to return the equipment to the defined process windows if divergent parameters are detected.
A prerequisite for mounting the measurement module to the EFEM instead of a load port, however, is that the measuring equipment is no wider or deeper than a load port and thus meets the standardized dimensions defined in SEMI Standard E 15.